We are seeking quantitative associations among the following processes as a means for developing both on the mechanism of carcinogenesis and a pre-screen for environmental carcinogens: Oncogenic transformation, cytotoxicity, chemical mutagenesis, DNA synthesis, and the production and repair of alkali-labile lesions in cellular DNA. This is done with cultured fibroblasts (Chinese hamster V79 and mouse embryo C3H/10T1/2 cells) treated with various doses of several simple alkylating agents.